Bad Luck or just Odds on Legendary Tokens?

So there are now 18 4-star and 2 5-star characters for a total of 60 different covers. Of these 60, I have three maxed out (IW yellow, XF black, and HB red). I have opened 8 legendary tokens and of course got IW yellow, XF black and 6 other 4 stars. What are the natural odds on that happening?